Field of the Invention
The present disclosure relates to an inkjet printing apparatus and an inkjet printing method.
Description of the Related Art
An inkjet printing method is a method where ink droplets are deposited on a printing medium to perform printing. Since this method has a simple printing process, multiple color printing can be performed at low cost. The method is non-contact printing, hence overprint can be realized and printing quality is easily improved and high speed printing can be performed without any noise. Therefore, the above-mentioned method has been widely used for from printers for domestic use to industrial printers.
Satisfactory image quality of from letter images through photographic images can be obtained by the inkjet printing method. Therefore, the inkjet printing method has been widely used as a method for outputting photographs instead of silver halide photograph, owing to recent popularization of digital cameras and scanners. Along with this trend, users have desired coloring of a printed output image close to coloring on a display in order to compare an image on a computer display with the printed output image and therefore image quality exceeding image quality of silver halide photographs has been desired.
As photographic image quality of inkjet printing, it is particularly desired that granularity is prevented as well as obtaining high resolution and gradation. Therefore, proposed is a method for achieving gradations using 2 types of inks having the identical hue but mutually different dye concentrations (see, for example, Japanese Unexamined Patent Application Publication No. 64-1545, Japanese Patent No. 1839472, and Japanese Patent No. 2859296).
Moreover, minimization of ink droplets has been studied in order to achieve high image quality. For example, in Japanese Unexamined Patent Application Publication No. 2000-141655, the invention where diameters of ink supply holes are made to be 30 μm or less is disclosed.
In Japanese Unexamined Patent Application Publication No. 2004-90233 furthermore, the invention where diameters of ink discharge openings of a nozzle are made to be 12 μm or greater but 22 μm or less is disclosed.